Railway traffic controlling apparatus



May 2, 1939.

R. R. KEMMERER RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Sept. 15, 1958 3 Sheets-Sheet l K bh w @QW SQ QM INVENTOR $362911 mePeJ? HIS ATTORNEY May 2, 1939. R. R. KEMMERER RAILWAY TRAFFIC CONTROLLING APPARATUS Filed Sept. 15, 1938 5 Sheets-Sheet 6 m MNN mm W m l A w Rmdm H Q @Q HAQ g V. W L m mm" W R 5mm. R5 mm @W Ra m? FL Rm 5 5RD V 5% am kfiw wk k3 N Patented May 2, 1939 UNITED STATES PATENT OFFlCE RAILWAY TRAFFIC CONTROLLING APPARATUS Application September 15, 1938, Serial No. 230,084

19 Claims.

My invention relates to railway traffic controlling apparatus and more specifically to apparatus for stopping the operation of highway crossing signals, operating detector locking track circuits, as well as for clearing out detector track sections generally in signalling systems employing one form of track circuit current, such as coded current, for the control of Wayside and cab signals and another form of track circuit current, such as uncoded current, for clearing out the highway crossing signals or other detection apparatus.

One feature of my invention is the provision of apparatus of the above character in which the code following track relay which controls the usual wayside signals is not required to perform the clearing out operation for the highway crossing signals, the latter function being performed by other apparatus selectively responsive to the uncoded energy which is provided for the purpose of signal clearing or track circuit detection. In this manner, the danger of improper signal operation due to an accidental failure of the code fo1- lowing track relay to operate is diminished and the safety factor of the system as a whole is increased.

I shall describe several forms of railway traffic controlling apparatus embodying my invention and shall then point out the novel features thereof in claims.

In the accompanying drawings, Figs. la and 11) when placed end to end with Fig. lb at the right, are a diagrammatic View of a stretch of railway track showing apparatus embodying my invention as applied to the clearing out of a pair of highway crossing cut sections upon the passage of a train. Fig. 2 is a diagrammatic view showing a modified form of the right hand portion of the apparatus of Fig. la, also embodying my invention. Fig. 3 is a diagrammatic view similar to certain portions of Figs. 1a and lb, showing apparatus embodying my invention in which the track circuits are supplied with direct current codes for wayside signal control and alternating current codes for cab signal purposes.

Similar reference characters refer to similar parts in each of the several views.

In coded wayside and cab signalling systems which include the control of highway crossing apparatus or the performance of other track detection functions, it is desirable that the current which is used for clearing out the highway crossing apparatus be of such character as to perform the desired wayside control function without at the same time interfering with the proper operation of the usual wayside and cab signals. These should, of course, not respond to the presence of such control or detection current in the rails. One manner in which this selective operation can be obtained is by using coded current for the control of the wayside and cab signals and using uncoded or so-called steady energy for the control of the highway crossing or other detection apparatus. One form of apparatus making use of steady energy for track detection purposes in a coded wayside and cab signal system is that disclosed in the copending joint application Serial No. 230,083, filed by me and Howell N. Dixon on Sept. 15, 1938, for Railway traffic controlling apparatus. The present application is also an improvement on the copending application Serial No. 210,744 filed by F. H. Nicholson and L. R. Allison on May 28, 1938, for Railway trafiic controlling apparatus.

As mentioned above, by making use of steady or uncoded energy in the rails, a distinctive response of the code following track relay, can. be obtained which response can be used for the selective control of the highway crossing or other apparatus without at the same time causing an undesired response of the cab or wayside signals. These, as is well known, will usually require the presence of coded impulses in the rails before operation of the wayside decoder will take place or before an operating voltage will be transmitted to the cab signalling apparatus.

One advantage of coded wayside signalling systems over systems of the usual steadily energized track circuit type is that the former systems possess a high degree of foreign current protection. Where steady energy is used for the clear ing out of highway crossing apparatus, however, the code following track relay is ordinarily incapable of distinguishing between the presence of such steady energy and the presence of some foreign current which may have entered the track system. Accordingly, if the steadily energized condition of the code following track relay itself is used for the purpose of providing highway crossing control, a certain amount of foreign current protection may be lost thereby. Moreover, the design of the usual code following track relay is such that it is considered a safety type relay only when performing a code following or dynamic function, in contrast with a. steadily energized or static function in which its front contacts remain constantly closed.

My apparatus disclosed herein is directed to overcoming the above disadvantages, and I accomplish this result by providing apparatus which is separate and apart from the code following track relay itself and which responds selectively to the presence of steady energy in the rails for the purposes herein set forth without in any manner interfering with the proper operation of the remaining apparatus.

Referring now to Figs. 1a and 1b of the drawings, I have shown herein a stretch of railway track comprising the block section A-D which is subdivided by means of insulated joints at the highway crossing locations B and C into the track circuit sections A-B, B-C and CD. These track circuit sections are, of course, necessary for the proper control of highway crossing apparatus at points B and C. Traffic in the block A-D normally moves from left to right in the direction of the arrow, entering traffic being controlled by the wayside signal SA and leaving traffic being controlled by another wayside signal SD. Each track circuit section is provided with a code following track relay designated by the reference character TR with a suffix corresponding to the location. As shown, these code following relays are of the direct current type and are energized from the track rails through a transformer-rectifier combination designated by the reference character It with a corresponding sufiix. The energy received by these track relays is supplied from a suitable track transformer T located at the other end of the track circuit, the primary of which is energized from a source of alternating or other periodic current (not shown) having the terminals BX--CX.

Depending on the condition of trafiic in advance of the block A-D, this source of current may be coded at a rate of either 180 or '75 times per minute by suitable code transmitters CTI80 and CT15 which are provided at the wayside signal location D, These code transmitters may be either of the constantly operating type, as shown, or may be approach controlled in any suitable and well known manner. Provision is also made for supplying steady or uncoded energy to certain of the track circuits of section A--D for the purpose of clearing out or stopping the operation of highway crossing signals XSB and XSC in a manner to be set forth in detail hereinafter. The highway crossing signals XSB and X80 are controlled by suitable interlocking relays XRB and XRC, respectively. Since the control circuits which connect these relays with the signals are well known, these circuits are not shown in the drawings in order to simplify the disclosure.

I shall first describe the operation of the individual apparatus at the various locations of the block A-D, and shall then describe the sequence of events as a train passes through the block section.

Looking first at location A, when the track relay TRA is following code, it alternatively energizes the input circuit of the decoding transformer DTA with direct current of normal and reverse polarity from a suitable direct current source (not shown) having the terminal 13-43. This periodic reversal of energy in the input circuit of transformer D'I'A causes an output to be delivered to the decoding relays HA and DA through the transformer-rectifier units RlEA and Rl80A, respectively. Unit RISBA is suitably tuned in well known manner whereby relay DA will respond only when the track relay is following [80 code, but the unit R15A is untuned, so that relay HA will operate both when the received code is I80 and also when it is 75. The

code received by the track relay TRA will be I80 when the block in advance of location D is unoccupied and will be 15 when this advance block is occupied by a train. When either of the track circuit sections BC or CD are occupied, the track relay TRA will receive uncoded energy, as will appear more fully hereinafter.

In conjunction with each code following track relay I have provided an auxiliary track relay ATR which performs the function of controlling the clearing out of the highway crossing apparatus. This auxiliary track relay is so designed that it will not follow code and will have a sulficiently long slow release period to permit certain operations later to be described to be performed before a release of this relay takes place. At location A, this auxiliary track relay is A'IRA and is controlled over the back contact 5-6 of the decoding relay I-IA in such a manner that whenever the decoding relay is deenergized, the auxiliary track relay will be connected in multiple with the code following track relay TRA for energization from the rails of the track circuit AB.

Normally, whenever coded energy is received by the track relay TRA, the decoding relay EA will be maintained energized. Therefore, the circuit for energizing the auxiliary track relay ATRA will not be completed at such time so that this relay will remain deenergized. However, when the track circuit A-B is energized with steady or uncoded energy in a manner to be described hereinafter, the track relay TRA will be at rest so that relay HA will be deenergized and will complete the circuit which connects relay ATRA in multiple with the track relay TRA.

The coded energy which is supplied to track circuit C--D is repeated into the track circuit BC by means of the track relay TRC (which, in following code, periodically interrupts the circuit for the track transformer TC at its contact 28-49) and is again repeated from the latter track circuit by means of the relay TRB into the track circuit A-B. Similarly, if the track circuit C-D is supplied with steady energy, this energy is likewise repeated due to the steadily energized condition of the respective track relays, into the two track circuts 3-0 and A-B in the rear thereof.

Looking next at location B in Fig. 2, the back contact repeater relay BSB repeats or checks the periodic operation of back contact 24 of track relay TRB. Similarly, relay FSB repeats or checks the periodic closing of front contact 23 of the same relay, provided, of course, that relay BSB remains energized in the meantime so that its front contact l-8 remains closed. The retardation of relays BSB and FSB is such that these relays remain picked up during the respective code intervals involved in the operation of track relay TRB.

When steady energy is received by relay TRB, this relay will maintain its front contact 2-3 closed and so will cause relay BSB to become deenergized. As soon as relay BSB releases, contact :";-8 thereof will close and will cause the auxiliary track relay ATRB to become picked up on the steady energy received from the track circuit. As soon as front contact l8 of relay BSB opens, relay FSB will become deenergized, opening its front contact 9-552, which disconnects terminal BX of the source from the track transformer IB. As soon as back contact I l-l2 closes, this transformer will receive steady energy from the BX auto tap. The BX autotransformer tap may supply either a higher or a lower voltage to the track circuit A-B, depending upon the energy requirements made necessary by the energization of the auxiliary relay ATRA on steady energy, in addition to the track relay.

With the block AD unoccupied, the left-hand magnet of interlocking relay XRB normally receives energy over the front contact |3-l4 of decoding relay HA, and the right-hand magnet of this relay receives energy over the front contact Iii-l 6 of relay FSB. Accordingly, with the apparatus as shown in the drawingathe highway crossing signal XSBwill not be operating, since both magnets of relay XRB are then energized. Similarly, the left-hand magnet of relay XRC is energized over a front contact l'l-IB of relay FSB and the right-hand magnet of this relay is energized over the front contact 23-24 of relay FSC and front contact 2l-22 of relay BSC.

Since the track circuit C-D never receives any steady energy, no auxiliary track relay is required for this track circuit, so that, only the track relay TRC and its associated relays FSC and BBC are required to control the right-hand magnet of the interlocking relay XRC.

Having described the operation of the individual apparatus, I shall now describe the operation which takes place when a train passes through the block section A-D from left to right.

When the train enters the track circuit A-B, the track relay TRA will become shunted and the relays HA and DA will therefore become deenergized. The closing of back contact 5-45 of relay HA will cause relay ATRA to become connected in multiple with track relay TRA but relay ATRA will not pick up because its energy is shunted out by the train at this time. The release of relay HA will also cause the front contact l3l4 toopen, thereby deenergizing the left-hand magnet of interlocking relay XRB so as to start the operation of the highway crossing signal XSB upon the entry of the train into the track circuit A-B.

As soon as the train enters the track circuit BC, the track relay TRB will become deenergized and will therefore cause relay FSB to become deenergized. The release of relay FSB will cause front contact 15-46 of this relay to open and thus to deenergize the right-hand magnet of relay XRB, but this will have no effect on the condition of the interlocking relay because of the previous deenergization of its left-hand magnet, The opening of front contact l'll8 of relay FSB will cause the deenergization of the left-hand magnet of interlocking relay XRC, thereby starting the operation of the crossing signal XSC due to the entry of the train into the track circuit BC.

As soon as the rear end of the train passes completely out of the track circuit A-B, steady energy will be fed to this track circuit by virtue of the closing of back contact lll2 of relay FSB, thereby steadily energizing the relays ATR andATRA of track circuit A-B. The energization of relay ATRA will cause front contact l920 of this relay to close so as to reenergize the left-hand magnet of interlocking relay XRB, thereby stopping the operation of the crossing signal XSB. The energizing circuit for relay HA is so designed that this relay will not pick up on a single pick-up operation of the track relay TRA such as occurs when the steady energy is connected to the track circuit A-B.

When the train enters the track circuit C- D,

relay TRC will become shunted and will cause relay PS0 to become deenergized, which will, in turn, deenergize the relay BSC and will apply steady energy to the track circuit BC. The opening of front contact 23-24 of relay FSC will cause the right-hand magnet of relay XRC to become deenergized, but this, of course, will have no efiect on the operation of the crossing signal because of the previous deenergization of the lefthand magnet of this relay.

As soon as the rear end of the train passes completely out of the track circuit BC, the steady energy will become effective in this track circuit due to the removal of the train shunt and the auxiliary track relay ATRB will accordingly become picked up. Relay BSB will continue to receive energy during the time that the track relay 'lTRB is deenergized, therefore, as soon as the track relay TRB picks up, relay FSB will become energized due to the fact that contact 1-8 of relay BSB remains momentarily closed at this time. That is, there will be an interval of time during which front contacts 2-3 and L43 are both closed so that relay FSB will receive an impulse of energy. This momentary energization will cause the closing of front contact l'll8 of relay FSB to thereby energize the left-hand magnet of interlocking relay XRC and thus stop the operation of the highway crossing signal XSC.

Shortly after the pick up of relay TRB on steady energy, relay BSB will release, thus removing energy from relay FSB. On account of its slow release characteristic, however, the latter relay will remain picked up for a short interval of time. The closing of back contact 56 of relay BSB will cause relay ATRB to become energized before relay FSB finally releases, therefore, the circuits for the interlocking relay will not be opened during the transfer of the control from relay FSB to relay ATRB.

When the rear end of the train passes COll'lpletely outof the track circuit C-D, 15 code will be fed to this track circuit over contact 25 of code transmitter CT'IS and back contact 26-21 of relay HD. The first on impulse of current will energize the relays TRC and FSC, and the first off code interval will energize the relay BSC. Accordingly, contacts 23-24 and 2l22 of relays F and BSC, respectively, will become .closed to complete the energizing circuit for the right-hand magnet of relay XRC.

Up to the moment that relay BSC became thus energized, steady energy continued to be fed to the track circuit BC. The second on impulse in track circuit CD will cause the track relay TRC to pick up again, thus opening its back contact 28-49, and causing an interruption in the steady energy being fed to the track circuit BC which interruption forms the first off code interval in the energy supplied to that track circuit. This first off period in the code of track circuit BC will cause relay TRB to become deenergized, thus picking up relay BSB. Due to the slow release characteristics of relay ATRB, however, the opening of back contact 5-6 of relay BSB will not cause relay ATRB to release immediately, and not until after the occurrence of the next on impulse which causes relay PS3 to become energized. Accordingly, it will be apparent that the energization of the interlocking relay XRC will not be disturbed during the transfer interval which occurs between the pick up of relay FSB and the subsequent release of relay ATRB.

In a manner which will be clear from the fore- Iii going description, the code following operation of relay TRB will produce code intervals in the energy fed to track circuit AB so that relay TRA will operate on code and will cause the decoding relay HA to become picked up. When this happens, relay ATRA will become released and the control for the interlocking relay XRB will be transferred from contact l9--2D of relay ATRA to contact I3-l4 of relay HA. The apparatus for the entire block section AD will now have been restored to the same condition in which it is illustraed in the drawings.

Assume next that a train traveling in the reverse trafiic direction enters the block section A--D through the leaving track circuit CD. It will be apparent that the operation of the highway crossing signal XSC will be initiated as soon as the train enters this track circuit because the steadily deenergized condition of rack relay TRC will cause relays FSC and BSC to become deenergized, thus opening the circuit for the right-hand magnet of the interlocking relay XRC at contacts lS-lfl and 2 l-22 which will initiate the operation of the highway crossing signal XSC. Similarly, the subsequent entry of the train into the track circuit BC will cause the right-hand magnet of the interlocking relay XRB to become deenergized, thereby initiating the operation of the highway crossing signal XSB.

The above entry of the train into the track circuit CD in the reverse traflic direction will, of course, cause steady energy to be applied to the track circuits BC and AB. However, as soon as the rear end of the train completely vacates the track circuit CD, this track circuit will obviously become reenergized on code which is supplied to this track circuit by code transmitters CTI80 and CT'I5 in the manner previously described. Similarly, as soon as the track circuits B-C and AB become progressively vacated, these will become energized by code supplied in the manner previously explained by means of the code following action of the track relays TRC and TRB, respectively. Accordingly, when a train operating in the reverse traflic direction completely vacates the block section A--D, the apparatus of this section will again be restored to the identical condition in which it is illustrated in the drawings.

Considering for a moment the apparatus at the right-hand portion of Fig. 112, I have shown therein a somewhat different decoding transformer arrangement in which the decoding relay HD, instead of being supplied through a transformer-rectifier combination as in the case of relay HA of Fig. 1a, is supplied with energy from an independent secondary winding 33 on the decoding transformer over a contact on the code following track relay TRD, and a contact of the code detecting relay BSD. The code detecting relay BSD is energized from the voltage drop across a rectifier 34 which is included in the input circuit of the decoding transformer D'I'D When the back contact 2-4 of track relay TRD is closed.

The apparatus at the signal location D may, if desired, be substituted for that at the signal location A and this apparatus has an advantage in that the auxiliary track relay ATRD becomes disconnected from the track circuit, following the passage of a train, as soon as the first ofi code interval appears, without the necessity for requiring additional code following steps of the track relay TRD (as required by the apparatus at location A) during the time that the auxiliary track relay ATRD is being disconnected from the track section. In this manner, a greater degree of independence is maintained between the functions of the code following track relay which controls the Wayside signals, and the auxiliary track relay which controls the stopping of the operation of the highway crossing signals.

Referring now to Fig. 2, which shows a modified form of the apparatus illustrated immediately above in the right-hand portion of Fig. 1a, I have shown in this figure a series connection for the auxiliary track relay A'IR and the code following relay TR, instead of the multiple connection shown in the figures thus far described. In all other respects, however, this apparatus is the same as the corresponding apparatus of Fig. 1a. It will be obvious, of course, that the series connection of Fig. 2 may be used in place of the multiple connection for the auxiliary track relay ATR at any of the locations A, B, or D of Figs. la and lb. It will be understood that when the series connection is used, the energization of the track circuits will be correspondingly adjusted, if necessary, so as to permit satisfactory pickup operation of the auxiliary track relay when this relay is connected in series with the code following track relay.

Referring now to Fig. 3, this figure shows an entering portion E--F of a block section, similar to the entering portion AB of the block AD in Figs. la and 112, except that in Fig. 3, the track circuits or wayside signal control apparatus employs coded direct current instead of coded a1- ternating current, the coded alternating current being used for the control of cab signals only. In this figure, therefore, the track relays TR]! and TRF may be connected directly with the rails of the track without the necessity for the transformer-rectifier units such as are shown in Figs. la and lb. Batteries BE and BF are included in the secondary circuits of the respective track transformers TE and TF for the purpose of supplying direct current code to the track circuits. Instead of coding the primary winding of the track transformer directly over a contact of the respective track relay, as in Figs. 1a and 1b, the apparatus of Fig. 3 employs code transmitting relays CTRE and CTRF for this purpose. These code transmitting relays follow or repeat the operation of the contacts of the respective code transmitters CTI80 or CT15, which contacts are included selectively in the energizing circuits of these relays.

It will be apparent that when the code transmitting relay CTRF, for example, is operating,

direct current code will be supplied to the track circuit EF for Wayside signal control and alter nating current code will be simultaneously supplied to this track circuit for the control of cab signalling apparatus. If, it is desired to. increase the track circuit energization when uncoded energy is fed to the track circuit, this may conveniently be accomplished by short-circuiting a portion of the track feed resistor 32 over the back contact -3l of relay FSF. In all other respects, however, the operation of the apparatus of Fig. 3 is similar to that of the apparatus in Figs. la and 1b, and will be understood Without further description.

It will be apparent from the foregoing that I have provided a coded wayside and cab signalling system in which the use of uncoded energy in the rails for performing certain control functions does not interfere with the proper safety operation of the usual code following track relay and does not decrease the foreign current protection provided by this relay. Furthermore, I have provided means for normally maintaining the auxiliary apparatus which is responsive to the uncoded energy disconnected from the track circuit so as to economize the track circuit power and thereby increase the permissible length of the track circuits which are involved. Also, I have provided means effective upon the exit of a train from the block for quickly disconnecting the auxiliary apparatus and restoring the track circuits to their normal condition of code operation. In addition, I have so designed the apparatus that proper protection of the highway crossings and effective restoration of the track circuits to their normal condition will take place irrespective of the direction which traffic may take over the section.

Although I have herein shown and described only a few forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination with a section of railway track, means for at times supplying coded current and for at other times supplying uncoded current to the rails of said section, a code following track relay receiving energy from the rails of. said section, an auxiliary track relay incapable of following impulses of said coded current but responsive to said uncoded current, means controlled by said code following track relay effective at said other times for connecting said auxiliary relay to receive energy from the track thus causing said auxiliary track relay to respond to said uncoded current, and traffic controlling apparatus governed by said auxiliary track relay.

2. In combination with a section of railway track, means for at times supplying coded current and for at other times supplying uncoded current to the rails of said section, a code following track relay receiving energy from the rails of said section, an auxiliary track relay incapable of following impulses of said coded current but responsive to said uncoded current, means controlled by said code following track relay effective at said other times for connecting said auxiliary relay to receive energy from the track thus energizing said auxiliary track relay on said uncoded current, and track detection apparatus governed by said code following and said auxiliary track relay.

3. In combination with a section of. railway track, means for at times supplying coded current and for at other times supplying uncoded current to the rails of said section, a code following track relay receiving energy from the rails of said section, a decoding relay energized in response to the code following action of said track relay, an auxiliary track relay incapable of following impulses of said coded current but responsive to said uncoded current, means controlled by said decoding relay effective at said other times for connecting said auxiliary relay to receive energy from the track thus energizing said auxiliary track relay on said uncoded current, and track detection apparatus governed by said auxiliary track relays.

4. In combination with a section of railway track, means for at times supplying coded current and for at other times supplying uncoded current to the rails of said section, a code following track relay receiving energy from the rails of said section, a decoding relay energized in response to the code following action of said track relay, an auxiliary track relay incapable of following impulses of said coded current but responsive to said uncoded current, means effective when said decoding relay is deenergized for at said other times connecting said auxiliary relay to receive energy from the track thus energizing said auxiliary track relay on said uncoded current, and track detection apparatus governed by said auxiliary track relay.

5. In combination with a section of railway track, means for at times supplying coded current and for at other times supplying uncoded current to the rails of said section, a code following track relay receiving energy from the rails of said section, a decoding relay energized in response to the code following action of said track relay, an auxiliary track relay incapable of following impulses of said coded current but responsive to said uncoded current, means effective at said other times and including a back contact of said decoding relay for connecting said auxiliary relay to receive energy from the track thus energizing said auxiliary track relay on said uncoded current, signalling apparatus, a first control circuit for said signalling apparatus including a front contact of said decoding relay, and a second control circuit for said signalling apparatus including a front contact of said auxiliary track relay.

6. In combination with a section of railway track, means for at times supplying coded current and for at other times supplying uncoded current to the rails of said section, a code following track relay receiving energy from the rails of said section, a decoding relay energized in response to the code following action of said track relay, an auxiliary track relay incapable of following impulses of said coded current but responsive to said uncoded current, means controlled by said decoding relay for at said other times connecting said auxiliary relay to receive energy from the track thus causing said auxiliary track relay to become energized on said uncoded current, train governing apparatus controlled by said code following track relay, and track detection apparatus governed by said auxiliary track relay.

'7. In combination with a section of railway track, means for at times supplying coded current and for at other times supplying uncoded current to the rails of said section, a code following track relay receiving energy from the rails of said section, a decoding relay energized in response to the code following action of said track relay, an auxiliary track relay incapable of following impulses of said coded current but responsive to said uncoded current, means controlled by said decoding relay for at said other times connecting said auxiliary relay to receive energy from the track thus causing said auxiliary track relay to become energized on said uncoded current, train governing apparatus controlled by said code following track relay, and track detection apparatus governed by both said decoding relay and said auxilary track relay.

8. In combination with a section of railway track, means for at times supplying coded current and for at other times supplying uncoded current to the rails of said section, a code following track relay receiving energy from the rails of said section, an auxiliary track relay incapable of following impulses of said coded current but responsive to said uncoded current, means controlled by said code following track relay effective at said other times for connecting said auxiliary relay to receive energy from the track thus energizing said auxiliary track relay on said uncoded current, train governing apparatus controlled by said code following track relay, and track detection apparatus governed by said auxiliary track relay.

9. In combination with a section of railway track, means for at times supplying coded current and for at other times supplying uncoded current to the rails of said section, a code following track relay receiving energy from the rails of said section, an auxiliary track relay incapable of following impulses of said coded current but responsive to said uncoded current, means controlled by said code following track relay effective at said other times for connecting said auxiliary track relay to receive energy from the track in multiple with the code following track relay whereby said auxiliary relay will become energized on said uncoded current, and track detection apparatus governed by said auxiliary track relay.

10. In combination with a section of railway track, means for at times supplying coded current and for at other times supplying uncoded current to the rails of said section, a code following track relay receiving energy from the rails of said section, an auxiliary track relay incapable of following impulses of said coded current but responsive to said uncoded current, means controlled by said code following relay effective at said other times for energizing said auxiliary track relay on said uncoded current over a series connection with said code following track relay, and track detection apparatus governed by said auxiliary track relay.

11. In combination with two adjoining sections of railway track intersected by a highway, means for at times supplying coded current and for at other times supplying uncoded current to the rails of said two sections, a code following track relay and an auxiliary track relay for each of said sections, said auxiliary track relays being incapable of following impulses of said coded current but responsive to said uncoded current, a decoding relay for each of said sections controlled by the associated code following track relay, means governed by each decoding relay effective at said other times for energizing the associated auxiliary track relay on said uncoded current, an interlocking relay for governing highway crossing apparatus at said highway intersection, means for controlling one magnet of said interlocking relay governed by the decoding relay and the auxiliary track relay for one of said sections, and means for controlling the other magnet of said interlocking relay governed by the decoding relay and the auxiliary track relay for the other of said two sections.

12. In combination with a section of railway track, means for at times supplying coded current and for at other times supplying uncoded current to the rails of said section, a code following track relay receiving energy from the rails of said section, a decoding relay energized in response to the code following action of said track relay, 2. slow release auxiliary track relay incapable of following impulses of said coded current but responsive to said uncoded current, means effective at said other times when said decoding relay is deenergized for energizing said auxiliary track relay on said uncoded current, said release period of the auxiliary track relay being sufficient to permit pick up of said decoding relay upon restoration of code to said section before the release of said auxiliary track relay, and track detection apparatus governed by said decoding relay and said auxiliary track relay.

13. In combination with a section of railway track, means for at times supplying coded current and for at other times supplying uncoded current to the rails of said section, a code following track relay receiving energy from the rails of said section, a decoding relay energized in response to the code following action of said track relay, an auxiliary track relay connected in series with said code following track relay and in capable of following impulses of said coded current but responsive to said uncoded current, means effective when said decoding relay is energized for shunting the current away from said auxiliary track relay whereby said auxiliary relay will become energized at said other times when said decoding relay is released and said shunt is removed, and track detection apparatus governed by said auxiliary track relay.

14. In combination with two adjoining sections of railway track intersected by a highway, means for supplying coded current to the rails of said two sections, means for at times supplying uncoded current to the rails of one of said sections, a code following track relay for each of said two sections, a decoding relay for each section energized in response to the code following action of the associated track relay, an auxiliary track relay for said one section incapable of following impulses of said coded current but responsive to said uncoded current, means governed by the decoding relay for said one section effective at said times for energizing said auxiliary track relay on said uncoded current, an interlocking relay for governing highway crossing apparatus at said intersection, circuits for controlling one magnet of said interlocking relay governed by the decoding relay and the auxiliary relay for said one section, and a circuit for the other magnet of said interlocking relay governed by the decoding relay for the other of said two sections.

15. In combination with two adjoining sections of railway track intersected by a highway, means for supplying coded current to the rails of each of said sections, a code following track relay for each of said sections, a decoding relay for each section energized in response to the code following action of the associated track relay, means effective when a train progresses into the forward one of said two sections for supplying the rear section with uncoded current, an auxiliary track relay incapable of following impulses of said coded current but responsive to said uncoded current, means controlled by the decoding relay for said rear section for energizing said auxiliary track relay on said uncoded current as soon as the train vacates said rear section, and highway crossing apparatus controlled jointly by the decoding relay for said forward section and the decoding relay and auxiliary track relay for said rear section.

16. In a coded track circuit system of wayside signalling in which a code following track relay is used for controlling wayside signals and uncoded track energy is used for providing track circuit detection when a train vacates the section, in combination, a normally inoperative auxiliary track relay incapable of following impulses of coded energy but responsive to uncoded energy, means controlled by the code following track relay effective upon the exit of the train from said section for connecting said auxiliary relay to receive energy from the track thus rendering said auxiliary track relay operative on said uncoded energy, and track circuit detection apparatus governed by said auxiliary track relay for detecting the exit of the train from said section.

17. In a coded track circuit system of wayside signalling in which a code following track relay is used for controlling wayside signals and uncoded track energy is used for providing track circuit detection when a train vacates the section, in combination, an auxiliary track relay normally disconnected from the track circuit and incapable of following impulses of coded energy, a decoding relay normally maintained energized due to the code following action of the code following track relay, means controlled by said decoding relay effective when uncoded energy is supplied to the track circuit and the code following track relay ceases to follow code for connecting said auxiliary track relay so that it will receive uncoded energy from the track circuit, and track circuit detection apparatus governed by said auxiliary track relay for detecting the exit of the train from said section.

18. In combination with two adjoining sections of railway track, means for supplying coded current to the rails of each section, a code following relay for each section, a decoding relay for each section controlled by the associated code following relay, an auxiliary track relay for one of said sections incapable of following impulses of coded current but responsive to uncoded current, means for at times supplying uncoded current to the rails of said one section, means controlled by the decoding relay for said one section effective at said times for energizing said auxiliary track relay on said uncoded current, means governed by the decoding relay for the other of said sections for controlling the amount of uncoded current which is supplied to said one section, and track detection apparatus governed by said auxiliary track relay.

19. In combination with two adjoining sections of railway track, means for supplying coded current to the rails of each section, a code following relay for each section, a decoding relay for one of said sections energized in response to the code following action of the associated code following track relay, an auxiliary track relay for said one section incapable of following impulses of coded current but responsive to uncoded current, means for at times. supplying uncoded current to the rails of said one section, means controlled by said decoding relay effective at said times for energizing said auxiliary relay on said uncoded current, means governed by the code following track relay for the other of said sections for controlling the amount of uncoded current which is supplied to said one section, and track detection apparatus governed by said auxiliary track relay.

RALPH R. KEMMERER. 

